Crest factor reduction (CFR) using asymmetrical pulses

Abstract

Crest factor reduction (CFR) techniques are provided using asymmetrical pulses. A crest factor reduction method comprises obtaining one or more data samples; detecting at least one peak in the one or more data samples; performing peak cancellation on the at least one detected peak by applying an asymmetric cancellation pulse to the at least one detected peak; and providing processed versions of the one or more data samples. The asymmetric cancellation pulse is generated, for example, by a minimum phase filter and has a substantially minimum group delay. New peaks associated with peak re-growth are introduced substantially only to the one side of the asymmetric cancellation pulse. The process can optionally rewind by an amount greater than or substantially equal to a group delay of the asymmetric cancellation pulse to address the limited number of pre-cursors that may be present in the asymmetric cancellation pulse.

We claim: 
     
       1. A crest factor reduction method, comprising the steps of:
 obtaining one or more data samples; 
 detecting at least one peak in said one or more data samples; 
 performing peak cancellation on said at least one detected peak by applying an asymmetric cancellation pulse to said at least one detected peak, wherein said asymmetric cancellation pulse is generated by a minimum phase filter and has a substantially minimum group delay; and 
 providing processed versions of said one or more data samples, wherein at least one of said detecting and performing steps are performed by at least one hardware device. 
 
     
     
       2. The method of  claim 1 , wherein said asymmetric cancellation pulse comprises side taps substantially only to one side of a center tap of the asymmetric cancellation pulse, wherein said one side is in a direction said one or more samples are processed. 
     
     
       3. The method of  claim 2 , wherein said asymmetric cancellation pulse introduces new peaks associated with peak re-growth substantially only to said one side of said asymmetric cancellation pulse. 
     
     
       4. The method of  claim 1 , further comprising the step of rewinding said method by an amount greater than or substantially equal to a group delay of said asymmetric cancellation pulse before processing additional samples. 
     
     
       5. The method of  claim 1 , wherein said one or more data samples are processed one or more of sample-by-sample and as a block of data samples. 
     
     
       6. A digital processor configured to perform crest factor reduction, comprising:
 a memory; and 
 at least one hardware device, coupled to the memory, operative to: 
 obtain one or more data samples; 
 detect at least one peak in said one or more data samples; 
 perform peak cancellation on said at least one detected peak by applying an asymmetric cancellation pulse to said at least one detected peak, wherein said asymmetric cancellation pulse is generated by a minimum phase filter and has a substantially minimum group delay; and 
 provide processed versions of said one or more data samples. 
 
     
     
       7. The digital processor of  claim 6 , wherein said asymmetric cancellation pulse comprises side taps substantially only to one side of a center tap of the asymmetric cancellation pulse, wherein said one side is in a direction said one or more samples are processed. 
     
     
       8. The digital processor of  claim 7 , wherein said asymmetric cancellation pulse introduces new peaks associated with peak re-growth substantially only to said one side of said asymmetric cancellation pulse. 
     
     
       9. The digital processor of  claim 6 , wherein said peak cancellation rewinds by an amount greater than or substantially equal to a group delay of said asymmetric cancellation pulse before processing additional samples. 
     
     
       10. The digital processor of  claim 6 , wherein said one or more data samples are processed one or more of sample-by-sample and as a block of data samples. 
     
     
       11. A crest factor reduction block, comprising:
 an input port to receive one or more data samples; 
 one or more peak detector and pulse cancellers to detect at least one peak in said one or more data samples and perform peak cancellation on said at least one detected peak by applying an asymmetric cancellation pulse to said at least one detected peak, wherein said asymmetric cancellation pulse is generated by a minimum phase filter and has a substantially minimum group delay; and 
 an output port to provide processed versions of said one or more data samples. 
 
     
     
       12. The crest factor reduction block of  claim 11 , wherein said asymmetric cancellation pulse comprises side taps substantially only to one side of a center tap of the asymmetric cancellation pulse, wherein said one side is in a direction said one or more samples are processed. 
     
     
       13. The crest factor reduction block of  claim 12 , wherein said asymmetric cancellation pulse introduces new peaks associated with peak re-growth substantially only to said one side of said asymmetric cancellation pulse. 
     
     
       14. The crest factor reduction block of  claim 11 , wherein said one or more peak detector and pulse cancellers rewind by an amount greater than or substantially equal to a group delay of said asymmetric cancellation pulse before processing additional samples. 
     
     
       15. The crest factor reduction block of  claim 11 , wherein said one or more data samples are processed one or more of sample-by-sample and as a block of data samples.